Many boaters suffer from physical handicaps that make it difficult or risky for them to go back and forth between a dock and a moored boat on their own, or that require help from others who might themselves be put at risk in helping with the transfer.
Ships, loading docks and oilrig platforms are known to use large cargo and personnel transfer capsules and cages, often moved with gantry-type cranes, to transfer people and cargo between a ship and the dock or platform.
Large boats and large permanent docks are often provided with devices such as extendable ramps to help handicapped boaters, especially wheelchair users, to get from the dock to the boat and back again.
Smaller recreational boats and smaller docks typically lack room and support (and sometimes stability) for cranes and ramps. It is accordingly also known to use small dock-based swiveling lifts or hoists to transfer handicapped boaters on and off their boats. These use a fairly permanent mounting, take up significant space on the dock, and appear to require other people on the dock to operate the equipment and assist with loading and transfer. The handicapped boater himself generally seems to remain a passive transferee, which is often unsatisfying and might lead in some cases to giving up the enjoyable pastime of boating.
U.S. Pat. No. 5,709,154 to Schott discloses a boat-mounted monorail access system for making a boat handicapped-accessible. A battery powered chair assembly is suspended from an overhead monorail track system installed throughout the boat, whereby by activating a control mechanism an individual may maneuver anywhere in the boat where track is installed. Once an individual is seated in the chair assembly, the monorail system allows the individual to travel to the cabins, flying bridge, downstairs to the galley, outside to the rear deck for sunbathing or fishing or over the side to a dock. As an additional feature, a length of overhead track coupled to a hinge mechanism may be provided whereby the track may swing out over the side of the boat supported by a boom or to a support located on the dock, thereby permitting the monorail access system to be used to enter and disembark the boat. This system, however, appears to be expensive, complex to install, and suitable only for relatively large boats. It further requires additional boom and support structure on the boat and/or on the dock in order to transfer the boater between boat and dock, and the transfer would be subject to the rocking of the boat.
It is also known to use lifts and hoists for general invalid/patient/handicapped use in homes, hospitals, and even for raising and lowering people into and out of swimming pools. Examples include U.S. Pat. Nos. 6,085,368 to Robert et al.; 4,805,248 to Lunau; 6,315,138 to Dyson; 5,062,165 to Kerr; and 3,981,484 and 4,588,155 to James.
None of the foregoing transfer devices is particularly suitable for use in transferring people between small, often seasonal, docks in shallow water and small recreational boats housed in boat lifts.
Boat lifts come in different styles, but they generally have a rectangular frame anchored in the lakebed and a movable cradle that raises and lowers the boat into and out of the water next to the dock in response to a manual or electric lift drive. The boat lift surrounds the boat, and is often roofed with a canopy to protect the boat. Boats moored in such boat lifts present a special boarding challenge for handicapped boaters. The extra spacing from the dock created by the lift; the surrounding frame, lift cradle, and canopy structure; and the small, sometimes rickety nature of the dock make the use of traditional boat-side and dockside transfer devices impractical. The usual alternative is to rely on personal lifting help from family and friends, which can be risky for all involved.